Process for the manufacture of building blocks



V.- LEFEBURE July 1, 1941.

I rnocfiss FOR THE MANUFACTURE OF BUILDING BLOCKS Filed Oct 29 1937 viclol- Lgfebure GOO/O d. 0o 0 0 o G 0o 0 0 Q 000 /00Q0 000 0 0000 oo, o o

Patented July 1, 1941 PROGESS FOR THE MANUFACTURE OF BUILDING BLOCKS Application October 29, 1937, Serial No. 171,788 in Great Britain October 29, 1936 9 Claims.

This invention relates to building blocks, and more particularly to building blocks made of calcium sulphate plaster.

Building blocks made of calcium sulphate plasters are used at present for interior work such as partition walls and the inner wall in cavity wall construction, but their use for other purposes is limited by the comparatively low strength of the material. Proposals have been made to strengthen such blocks by means of metallic reinforcements such as wire gauze, which are placed in position before the mass has set, but the relatively high cost of metal and its susceptibility to corrosion, with consequent loss of strength, are serious drawbacks.

This invention has as an object to provide reinforced building blocks without these drawprincipal surfaces of the block, and if desired may extend around one or more of the remaining surfaces. Alternatively, the liner may be in two layers embedded in the block, each layer being a short distance e. g. 9 inch, away from one of the principal surfaces of the block and parallel thereto. A convenient method of introducing the two layers consists in bending a sheet of the paper or pulp board into a rough U-shape and inserting it into the mould in which the block is formed.

The liner should have a high tensile strength for a given thickness and its surface should be fairly rough in order that the fibrous projections may assist in making a firm bond with the plaster. A suitable thickness of liner is 0015-01135 inch. Holes or a series of perforations may be formed in the liners embedded in the block, in order to provide a continuous body of plaster and to increase the transverse strength of the block resisting cleavage. Such holes or perforations, however, should not be unduly multiplied, as they tend to diminish the tensile strength of the block in the plane of the liners.

If desired the liner may be of similar form to corrugated paper, having hollow tubes which assist in reducing the density of the block by introducing air spaces. To increase the adhesion of the plaster the liner may be previously rubbed or otherwise treated with a slurry of calcium sulphate plaster, preferably the same plaster as is used for the manufacture of the block. The strength of the liner under wet conditions may be increased by sizing or impregnating it with suitable media, e. g. a solution of sodium silicate and aluminum sulphate. A liner containing up to 50 per cent. of asbestos may be used to increase the fire resistance and to ensure that the strength of the block is not unduly diminished by exposure to high temperatures. The placing of the liner in a mould in such a manner that it is not substantially displaced during pouring of the plaster or during the rising of the mass in the case of a gas-generating plaster, requires care.

The following example illustrates one convenient procedure in making a block, with reference to the accompanying drawing.

Example Figure l is a perspective sketch of a mould (a) suitable for the block.

Figure 2 is a sketch of the paper board (2)) reinforcement before it is folded.

Figure 3 is a sketch of the paper board reinforcement folded ready for placing in the mould.

Figure 4 is a sketch of a wire former (c) The procedure adopted when making blocks by this method is firstly to fill the mould (a) with unset plaster, then to fold the paper board liner (b) round the wire former (c) and then to force the former and the liner into the unset plaster in the mould. The holes d, d, in the liner permit the plaster to flow round the liner without the formation of any air pockets, and, if a gas generating plaster is used these holes permit the passage of gas bubbles.

A paste is made up and applied to the surfaces to be joined, the preferred composition being as follows: Anhydrite plaster-{3% by weight of flour glue made up to a paste containing 18-30% by weight of water. The flour glue may be replaced by dextrin, gum arabic or other similar adhesives.

(c) Portland cement+casein. The preferred preformed blocks with the aid of a plaster slurry or a suitable adhesive.

The value of the invention is illustrated by the following tables, which show the results of breaking tests on the products of the present invention. In each case a block was placed on circular rods, spaced 15 inches between centres and the load was applied at the centre of the block.

Transverse strength blocks 7 Breaking Core load lbs. wt. Thickness density, Reinforcement Adhesive between lb./1t. 1

centres Plain blocks:

63.9 0.030 S. S. dz K. linen... Inserted internally 565 62.8 .do ..do 565 62. 3 ....do ..d0 560 G2. 0 0.030 Merton C. Board.... Inserted internally" 550 61.0 do ..do 540 607 .....do ..do 540 60. 0 0.030 'I. B. M. liner Inserted intcrnally.. 640

60.0 --.do ..d0 000 61.4 do -.do 565 59. 7 Inserted internally. 930

59.4 0.030 Merton C. Board-.. 600

58. 9 0.030 Merton C Board 800 proportion of casein is 5% by weight of the As many apparently widely different embodicement. ments of this invention may be made without de- (d) Hemi-hydrate plaster-l-casein. A paste containing 35-45% of water was made up with hemi-hydrate and casein, the proportion of casein'being 5% by weight of the hemi-hydrate.

Other mucila'ginous materials may be used.

The blocks may be made of any known kind of water-setting calcium sulphate plaster; I prefer to use plaster of Paris or a plaster of the accelerated anhydrite type. (By a plaster of the accelerated anhydrite type is meant a plaster the setting properties of which are due essentially to the hydration of anhydrous calcium sulphate under the influence of small proportions of suitable accelerators, such as alkali metal salts and certain metal sulphates, e. g. potassium sulphate, zinc sulphate, or aluminum sulphate.) I may also use mixtures of plaster of Paris and anhydrite, with or without accelerators for the hydration of the latter. Plasters giving void or cellular products, by the generation in known manner of foam or gas within the mass before or during setting, may also be used, the resulting blocks being 'of relatively low density and having increased heat and sound insulating capacity. The liners are preferably applied during the manufacture of the block, by placing them in the mould or introducing them into the mass as it is formed into slabs in the case where 'a'plastic or dough-like mass is shaped by means 'of rollers. In some 'cases the liners may be applied to the parting from the spirit and scope thereof it is to be understood that I do not limit myself to the specific embodiments thereof except as defined in the appended claims.

I claim:

1. A process for the manufacture of building blocks which comprises filling a mould with unset calcium sulphate plaster and inserting into the unset plaster a sheet of pulp board folded substantially into a U shape about a temporary support so that each limb'of the U rests substantially parallel to and within half an inch of two opposing surfaces of the plaster and removing the temporary support before the plaster hardens.

2. A process for the manufacture of building blocks which comprises filling a mould with unset calcium sulphate plaster, folding a sheet of pulp board around a wire former, inserting the former and the pulp board into the unset plaster and then removing the former, the dimensions of the former and the board being such that the former forms the board substantially into a U shape and places each limb of the U substantially parallel to and within half an inch of two opposing sides of the mould.

3. A process for the manufacture of building blocks which comprises forming a mass of plastic material, associating a sheet of fibrous reinforcing material with a rigid temporary support, in-

serting said support and sheet edgewise into said plastic material while rigidly supporting said sheet to prevent bending thereof while being inserted, removing the temporary support, and permitting said plastic material to harden after insertion of said sheet and after removal of said support.

4. A process for the manufacture of building blocks which comprises filling a mold with a mass of plastic material, associating a sheet of fibrous reinforcing material with a rigid temporary support, inserting said support and sheet edgewise into said plastic material while rigidly supporting said sheet to prevent bending thereof while being inserted, said sheet being inserted so that it is substantially parallel to and substantially coextensive with a face of the molded plastic material, removing the temporary support, and permitting said plastic material to harden after insertion of said sheet and after removal of said support.

5. A process for the manufacture of building blocks which comprises filling a mold with a mass of plastic material, folding a sheet of fibrous reinforcing material substantially into a U-shape, rigidly backing said U-shaped sheet and while thus rigidly backed inserting said sheet into said plastic material so that each limb of the U is inserted edgewise to lie substantially parallel to and between two opposing surfaces of the molded plastic material, removing said backing, and permitting said plastic material to harden after removal of said backing.

6. A process for the manufacture of building blocks which comprises filling a mold with a mass of plastic material, folding a sheet of fibrous reinforcing material substantially into a U shape about a rigid open support, inserting said support and the folded sheet, with the folded edge thereof foremost, into said plastic material so that each limb of the U lies substantially parallel to and between opposing surfaces of the molded plastic material, removing said support, and permitting said plastic material to harden after removal of said support.

7. A process for the manufacture of building blocks which comprises forming a block of plastic calcium sulphate plaster, folding a sheet of iibrous reinforcing material, provided with at least one opening, substantially into a U shape about a rigid open support so that the opening in the sheet appears in the folded edge thereof, inserting said support and the folded sheet, with the folded edge thereof foremost, into said plastic plaster whereby said plaster will flow through said opening and between the limbs of the U- shaped sheet of fibrous material, and whereby each limb lies substantially parallel to and between .OPposing surfaces of the plaster block, removing said support, and permitting said plaster to harden after removal of said support.

8. A process for the manufacture of building blocks which comprises forming a mass of unset calcium sulphate plaster, rubbing a sheet of fibrous reinforcing material with a slurry of calcium sulphate plaster, associating said sheet with a rigid temporary support, inserting said support and sheet edgewise into said mass of unset plaster while rigidly supporting said sheet to prevent bending thereof while being inserted, removing the temporary support and permitting said plaster to set after insertion of said sheet and after removal of said support.

9. A process for the manufacture of building blocks which comprises forming a mass of unset plastic calcium sulphate plaster in the shape of a block, associating a sheet of pulp board with a rigid temporary support, inserting said support and sheet edgewise into, and substantially parallel to at least one surface of, said mass of plaster while said plaster is in the plastic state and while rigidly supporting said sheet during said insertion, and removing said temporary support after insertion of said pulp board sheet and while the plaster is still in the plastic state.

VICTOR LEFEBURE. 

